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BD9V100MUF-C: A DC/DC Converter with the Industry's Highest Step-Down Ratio

DC/DC Converter IC with the Industry's Highest Step-Down Ratio at 2 MHz

  • BD9V100MUF-C
  • Minimum switching ON time
  • Step-down ratio
  • 2 MHz
  • 60 V
  • Two-step step-down replaced with single-step step-down
  • AM radio band
  • Mild hybrid vehicle
  • Automotive
  • 48 V
  • AEC-Q100
  • Wettable flank

In June 2017, ROHM began sample shipments of the BD9V100MUF-C DC/DC converter IC with the industry's highest step-down ratio, achieved with switching at 2 MHz, and in December 2017 announced that it would begin volume production.

Engineering samples of the BD9V100MUF-C were demonstrated at exhibits such as CEATEC in 2016, and the development had already been announced. Due to the high level of interest expressed, this device was immediately addressed in an "Ask Direct to Engineers" column (Japanese) of TECH INFO on ROHM's Tech Web, with the title " DC/DC Converter IC Capable of Direct Step-Down from 48 V to 3.3 V", consisting of two articles: Part 1: Is Direct Step-Down from 48 V to 3.3 V Possible? and Part 2: Simplifying the Power Supplies of 48 V Hybrid Systems to Cut Losses.

In this article, we shall go over the features and specifications of the BD9V100MUF-C that have been formally released. There are generally no changes to the basic functions and features described in the article mentioned above, but the specifications and ratings for the product were provisional at that time, and there have been some changes. The initial edition of the data sheet has also been released, and should be consulted for further details.

Synchronous Rectification DC/DC Converter IC Achieves Industry -High Step-Down Ratio at 2 MHz, Supports Automotive Applications

The BD9V100MUF-C is a MOSFET-based synchronous rectification DC/DC converter IC. Through Nano Pulse Control®, which is ultra-fast pulse control technology that utilizes an ultra-fast pulse control circuit and high-voltage BiCDMOS processes, the world's lowest* minimum switching ON time for a power supply IC of 9 ns was achieved, to realize an industry-high 24:1 step-down ratio.(*According to a 7/27/2017survey by ROHM)

Operating at 2 MHz, a high maximum input voltage of 60 V can be stepped down to a low 5 V or 3.3 V (minimum 2.5 V) for an automotive ECU. In the 48 V power supply systems of mild hybrid vehicles, the current two-step step-down can be replaced with single-step step-down. A single circuit suffices for the DC/DC converter, reducing the number of components by half and simplifying the power supply system as well.

First, we review the basic features and specifications as a power supply IC. The input voltage range is 16 V to 60 V, and the output is 0.8 V to 5.5 V, with up to a 1 A current maximum. The switching frequency can be set in the range 1.9 MHz to 2.3 MHz, chosen specifically for automotive uses so as not to affect the AM radio band (up to 1.84 MHz). The minimum switching ON time, which determines the step-down ratio, is 9 ns typ and 20 ns max. This is the most important feature of the BD9V100MUF-C; as the figure on the right indicates, existing products do not approach this level.


This product is provided with various protection functions such as soft start, and the application circuit employs standard synchronous rectification but is suitable for high-voltage application. A power MOSFET is incorporated to keep the time required for design to a bare minimum.

AEC-Q100 (Grade 1) is supported for use in automotive equipment, and wettable flank package is adopted. Wettable flanks are will be explained separately.

Below, features and recommended operating conditions are summarized.

BD9V100MUF-C Features

  • ・Direct conversion from 60 V to 3.3 V at 2.1 MHz
     is possible
  • ・AEC-Q100 compliant(Grade 1)
  • ・Minimum switching ON time: 20 ns (max)
  • ・Synchronous rectification method
  • ・Soft start function
  • ・Current mode control
  • ・Overcurrent protection function
  • ・Input undervoltage lockout function
  • ・Input overvoltage lockout function
  • ・Thermal shutdown protection function
  • ・Output overvoltage protection function
  • ・Load short-circuit protection function
  • ・Wettable flank QFN package

Recommended Operating Conditions

  • ・Operating supply voltage range: 16 V to 60 V
  • ・Operating ambient temperature range:
     –40 to +125 ℃
  • ・Output voltage range: 0.8 V to 5.5 V
  • ・Minimum switching ON time*1:
     9 ns (typ), 20 ns (max)
  • ・Output current range: 0 to 1 A
  • ・Switching frequencies:
     1.9 MHz (min), 2.1 MHz (typ), 2.3 MHz (max)
  • ・Input capacitor value*2: 1.2 µF (min)
  • ・Switching frequency setting resistor*3:
     6.9 kΩ, 7.5 kΩ, 8.1 kΩ
  • *1: This parameter is for 0.5 A output current.
     Not 100% tested.
  • *2: Ceramic capacitor is recommended.
  • *3: For switching frequencies min., typ. and max.

BD9V100MUF-C: A DC/DC Converter with the Industry's Highest Step-Down Ratio

Power Supply Design Technical Materials Free Download

Power Supply Design Technical Materials Free Download

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